Seismic device for insulating buildings

ABSTRACT

A seismic device for insulating buildings comprises a group of at least three plates ( 1, 2, 3 ) overlapping each other and having respective faces facing each other shaped to define, between each pair ( 1, 2; 2, 3 ) of facing plates, at least one pair of channels ( 12 ). Each channels ( 12 ) house at least one roller ( 5, 6 ) adapted to allow relative sliding in a horizontal plane of the plates ( 1, 2, 3 ) for the absorption of horizontal oscillations produced by an earthquake. The channels ( 12 ) between the lower plate ( 1 ) and the intermediate plate ( 2 ) have a development direction orthogonal with respect to the channels ( 12 ) defined between the intermediate plate ( 2 ) and the top plate ( 3 ) of the group. Elastic damping means are also provided and arranged below the group of plates ( 1, 2, 3 ) and comprise a plurality of cushions ( 9 ) inflated to a predetermined controlled pressure and arranged below the lower plate ( 1 ) to raise said group from the ground and absorb the load and the vertical oscillations produced by the earthquake.

TECHNICAL FIELD

The present invention finds application in the field of seismic devices and in particular relates with a seismic device for the insulation of buildings and constructions in general.

STATE OF THE ART

At present the seismic isolation techniques for protecting buildings from destructive violence of an earthquake involve the use of different types of isolation devices.

Among these, the most common systems involve the use of slide systems with overlapped metal plates, systems with metal plates and rubber plates placed one over the other in an alternate way, rubber cylinders with bases fastened to the structure, rolling ball or rollers systems, simple or double pendulum systems.

WO95/23267 discloses an insulating device formed by a pair of overlapping plates having opposite faces so shaped to define channels for housing rollers for the reciprocal sliding of the plates.

The top plate is also provided with additional channels in which two further rollers are housed and rotated 90° with respect to the lower rollers and on which a third plate rests to support the construction.

In this way, the rollers can absorb the oscillations in a horizontal plane produced by an earthquake.

The whole group of plates also rests on a group of elastic elements, in particular high-strength springs, which have the task of absorbing the vertical oscillations.

The use of these cushioning systems for absorption of the vertical oscillations has, however, some drawbacks, a first of which is represented by the high cost of such systems.

Furthermore, in the moment in which the absorption capacity of the loads has to be varied, it is necessary to provide different type of springs or to vary the number thereof, with possible problems of equilibrium of the device.

Moreover, in this case it is also necessary to proceed to the removal of the upper plates, which is clearly not always feasible.

Scope of the Invention

The object of the present invention is to overcome the above mentioned drawbacks, by providing a seismic device for insulating buildings with high efficiency and relative cheapness.

A particular object is to provide a seismic device for insulating buildings wherein the properties of absorbing vertical loads and vertical oscillations produced by the earthquake may be easily adjusted and adapted to the specific structure which the device is applied to. Still another particular object is to provide a seismic device for insulating buildings wherein the adjustment of the capacity of absorbing vertical loads may also be obtained with the device in assembled condition.

These objects, as well others which will appear more clearly hereinafter, are achieved by a seismic device for insulating buildings that, according to claim 1, comprises a group of at least three plates mutually superimposed and having respective faces facing each other and shaped to define, between each pair of facing plates, at least one pair of channels, each of said channels housing at least one roller adapted to allow relative sliding in a horizontal plane of said plates for absorption of horizontal oscillations produced by an earthquake, the channels defined by the lower plate and the intermediate plate having the extension direction perpendicular to the channels defined between said intermediate plate and the top plate. The device also comprises elastic damping means placed below said group of plates to isolate it from the vertical oscillations caused by an earthquake and that comprise a plurality of cushions inflatable at a predetermined controlled pressure and placed below said lower plate to raise said group from the ground and absorb the load thereof and the vertical oscillations produced by the earthquake.

In this way it will be possible to adjust the pressure of the cushions to the specific load conditions in an easy and immediate way, simply by varying the inflation pressure and without inserting or removing one or more damping elements.

Suitably, said cushions may comprise an elastomeric material inflating chamber provided with an inflation/deflation valve, so as to adjust pressure in a simple manner. Advantageously, the damping means may comprise a plurality of spacers adapted to be disposed below said lower plate to maintain said group raised from the ground by a distance sufficient to allow insertion of said cushions in the deflated condition for their next inflation at the predetermined pressure.

In this way it will not be necessary to position the cushions already inflated but the same may be introduced below the group of plates after placing the same group and in deflated conditions so as to be gradually brought to the correct pressure value.

Advantageous embodiments of the invention are obtained in accordance with the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become more apparent from the detailed description of some preferred but not exclusive embodiments of a seismic device for insulating buildings, illustrated by way of non-limiting example with the aid of the accompanying drawing in which:

FIG. 1 is a front view of the lower plate of the group of the invention and of two sides views of the same plate;

FIG. 2 is a front view of the intermediate plate of the group of the invention and of two sides views of the same plate;

FIG. 3 is a front view of the top plate of the group of the invention and of two sides views of the same plate;

FIG. 4 is a perspective view of the device of the invention in a first preferred embodiment;

FIGS. 5 and 6 are two front views of the device of FIG. 4 rotated of 90° with each other;

FIGS. 7 and 8 are two front views of a device in a second preferred embodiment rotated of 90° with each other;

FIG. 9 shows two possible embodiments of the rollers;

FIG. 10 shows an inflatable cushion in an inflated condition and in a deflated condition;

FIGS. 11 and 12 are two front views of the device in a third preferred embodiment rotated of 90° with each other;

FIGS. 13 and 14 are two front views of the device in a fourth preferred embodiment rotated of 90° with each other;

FIG. 15 shows a detail of the devices of FIGS. 11 to 14;

FIG. 16 shows the lower spacers of the device according a top view and side views.

BEST MODES OF CARRYING OUT THE INVENTION

With reference to the attached figures, there are illustrated some preferred but not exclusive embodiments of a seismic device for insulating building structures, such as buildings, bridges and infrastructure in general, designed to be arranged in correspondence of the supporting structures of a building in order to absorb the horizontal and vertical oscillations produced by a possible earthquake.

In its most basic configuration, the device, shown assembled in the operating configuration of FIG. 4, comprises a group of three plates 1, 2, 3 overlapping each other and having respective faces facing each other shaped to define, between each pair of facing plates, at least one pair of channels 12.

Each channel 12 houses one or more rollers 5 adapted to allow the relative sliding of the plates 1, 2, 3 in a horizontal plane for the absorption of horizontal oscillations produced by the earthquake.

In particular, the channels 12 between the lower plate 1 and the intermediate plate 2 have a direction of development perpendicular to the channels 12 between the intermediate plate 2 and the top plate 3 of the group.

Elastic damping means are arranged below the lower plate 1 for absorbing the upper load and isolating the group of plates 1, 2, 3, and consequently the upper construction, from the vertical oscillations caused by the earthquake.

The elastic damping means comprise a plurality of cushions 9 adapted to be inflated to a controlled predetermined pressure to raise the group from the ground and absorb the load and the vertical oscillations produced by the earthquake.

The number and the capacity of the cushions 9 may vary depending on the load and the size of the whole device, without particular theoretical limitations.

The cushions 9 will comprise an inflation chamber made of elastomeric material, for example rubber, provided with an inflation/deflation valve.

As shown from FIG. 10, the inflation chambers may have an annular shape. In this figure, the chamber 8 is in the deflated configuration while the chamber 9 is in inflated condition. The damping means also comprise a plurality of spacers 11 adapted to be arranged below the lower plate 1 to keep the group raised from the ground for a distance sufficient to allow insertion of the cushions 8 in deflated condition for subsequently inflating them to the predetermined pressure.

In this way, through the introduction of hydraulic jacks or similar means it will be also possible to temporarily bypass the device, for example in a maintenance phase.

The spacers 11 may be arranged directly on the ground or on a support 10 adapted to support the whole group of plates, as shown in FIG. 16.

The spacers 11 are arranged along the perimeter of the lower plate 1, in a variable number according to the dimensional requirements, with heights that can be selected in function of the dimensional features of the cushions 9, i.e. the height of the latter in the inflated condition, so that with inflated cushions 9 the lower plate 1 is raised with respect of the spacers 11.

From FIG. 1, wherein the lower plate 1 of the group is shown, it is visible that the plate 1 has a flat lower face and a shaped upper face on which two concavities identical with each other in shape and mutually parallel are realized, in relief or recessed.

Each concavity will define a rolling track for one or more rollers 5 and will face a corresponding concavity made in the lower face of the intermediate plate 2, so as to define two channels 12 for housing respective rollers 5.

The channels 12 defined between the lower plate 1 and the intermediate plate 2 will be parallel to each other to confer to the rollers 5 a same direction of rolling, allowing the horizontal relative sliding between the lower plate 1 and the intermediate plate 2 in a direction orthogonal to the axis of rotation of the rollers 5 for absorbing the respective horizontal components of the oscillations produced by the earthquake.

The upper face of the intermediate plate 2 is also shaped with a pair of concavities or rolling tracks facing upwards and which develop in a direction orthogonal to the concavities or tracks of the lower face.

Such concavities will face respective specular concavities of the lower face of the top plate 3, so as to define two further channels 12 for housing and rolling the rollers 5, always parallel to each other to have a same direction of rolling.

These further channels 12 will develop orthogonally to the channels 12 defined between the lower plate 1 and the intermediate one 2 to allow the relative horizontal sliding between the top plate 3 and the intermediate plate 2 in a direction orthogonal to the axis of rotation of the respective rollers 5 and allow the absorption of the respective horizontal components of oscillations produced by the earthquake.

In this way, the combined action of the rollers 5 arranged between the lower plate 1 and the intermediate plate 2 and of the rollers 5 between the intermediate plate 2 and the top one 3 will make it possible to absorb all the horizontal components of the stresses produced by the earthquake.

The lower plate 1 and the top plate 3 will be substantially similar to each other and be mutually rotated by 180° on the vertical plane and of 90° on the horizontal plane.

The rollers 5, of free-rolling type, self-centering, permanent and instantaneous for gravity will be substantially cylindrical with a circular or elliptical base, with axial extension close to that of the respective channels 12 and minimum diameter so to maintain the plates 1, 2, 3 mutually spaced apart in the vertical direction to prevent their mutual contact and the consequent friction.

The rollers 5 will present a hard and smooth outer surface with low friction coefficient, possibly mirror-polished, and may either be manufactured without guides or with removable guides, as shown in FIG. 9 wherein the rollers with guides are indicated by 6.

In turn, the concavities will be machined so as to have a hard and smooth outer surface with low friction coefficient, possibly mirror-polished.

In this way the device will be highly effective in the absorption of oscillations since the friction will be substantially null.

By contrast, the faces of the lower plate 1 and of the top plate 3 not provided with the concavities may be rough, with the top plate 3 having the upper face facing upwards that will constitute a single block with the above structure, while its lower face will isolate the structure from the ground.

More than one roller 5 having axes of rotation parallel with each other may also be housed in each channel 12.

For example, FIGS. 7 and 8 show a device having two rollers 5 for each channel 12. In FIGS. 11 and 12 three rollers 5 are instead present in each channel 12, while in FIGS. 13 and 14 every channel 12 houses four rollers 5.

In the case of three or more rollers 5 for each channel 12, the side rollers will have diameter smaller than the one of the central rollers to allow their insertion inside the channels 12 with a circular are section.

Moreover, in case of more rollers 5 in the same channel 12, these rollers 5 will have the respective axes of rotation mutually coupled by connecting rods, struts with bushings, ball bearings or other equivalent chain-mounted mechanisms, as shown in FIG. 15 wherein such means are indicated by 7, to maintain fixed the transverse distance of the rollers 5 and at the same time allow the rolling thereof, but preventing the rollers 5 to roll by gravity towards the center of the tracks, both in static conditions and during an earthquake.

The dimensions of the various parts of the device are not limiting nor significant for the present invention, as will be selected in function of the construction which the device is designed for.

From above it appears evident that the device according to the invention achieves the intended objects.

The device according to the invention is susceptible of numerous modifications and variations, all falling within the inventive concept expressed in the accompanying claims. All the details may be also replaced with other technically equivalent elements, and the materials may be different according to requirements, without departing from the scope of protection of the present invention.

Although the device has been disclosed with particular reference to the attached figures, the reference numbers used in the description and in the claims are used to improve the intelligence of the invention and do not constitute any limitation to the scope of protection claimed. 

1. A seismic device for insulating buildings, comprising: a group of at least three plates (1, 2, 3) overlapping each other and having respective faces facing each other shaped to define, between each pair (1, 2; 2, 3) of facing plates, at least one pair of channels (12), each of said channels (12) housing at least one roller (5, 6) adapted to allow relative sliding in a horizontal plane of said plates (1, 2, 3) for the absorption of horizontal oscillations produced by an earthquake, the channels (12) between the lower plate (1) and the intermediate plate (2) having a development direction orthogonal with respect to the channels (12) defined between said intermediate plate (2) and top plate (3) of said group; elastic damping means arranged below said group of plates (1, 2, 3) to isolate it from the vertical oscillations caused by an earthquake; characterized in that said elastic damping means comprise a plurality of cushions (9) inflated to a predetermined controlled pressure and arranged below said lower plate (1) to raise said group from the ground and absorb the load and the vertical oscillations produced by the earthquake.
 2. Device as claimed in claim 1, characterized in that said cushions (9) comprise an inflation chamber made of elastomeric material and provided with an inflation/deflation valve.
 3. Device as claimed in claim 1, characterized in that said damping means comprise a plurality of spacers (11) adapted to be disposed below said lower plate (1) for maintaining said group raised from the ground by a distance sufficient to allow the insertion of the deflated cushions (8) for their subsequent inflation to the predetermined pressure.
 4. Device as claimed in claim 1, characterized in that each shaped face of said plates (1, 2, 3) has a pair of identical and mutually parallel concavities, said concavities being specular to the concavities of the shaped face facing it and having a circular arc-shaped section.
 5. Device as claimed in claim 4, characterized in that said lower plate (1) and said top plate (3) have respective shaped faces identical to each other and are arranged in positions rotated 90° with each other.
 6. Device as claimed in claim 5, characterized in that said intermediate plate (2) has two mutually opposite shaped faces each having a pair of concavities defining the rolling tracks for said rollers (5, 6).
 7. Device as claimed in claim 6, characterized in that said concavities extend along mutually orthogonal directions parallel to the directions of development of the concavities formed in the shaped faces facing thereto to define respective housing channels (12) for said rollers (5, 6).
 8. Device as claimed in claim 1, characterized in that said rollers (5, 6) are sized with such a diameter as to hold said plates (1, 2, 3) mutually spaced apart and prevent the mutual contact.
 9. Device as claimed in claim 1, characterized in that each of said channels (12) houses at least two rollers (5, 6) having axes of rotation parallel with each other.
 10. Device as claimed in claim 9, characterized in that the rollers (5, 6) inserted in a same channel have respective axes of rotation mutually coupled by connecting rod or bearing means (7) so as to maintain fixed the transverse distance and to allow the rolling.
 11. Device as claimed in claim 9, characterized in that said rollers (5, 6) have a decreasing diameter from the center of said channels (12) towards the side edges thereof. 